PCI/doc: Convert examples to generic power management

PCI-specific power management (pci_driver.suspend and pci_driver.resume) is
deprecated.  Convert sample code to the generic power management framework.

Link: https://lore.kernel.org/r/20220607232946.355987-1-helgaas@kernel.org


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>